Simple sine wave demo

[kerunaru]

Okay… So yesterday I realised I don't know programming, at least, not all I thought I knew. One thing is web development and another thing is C programming for a tiny system like Gamebuino.

Auto-critic done, here goes my question. I'm trying to make a simple sine wave scrolling demo. My problem is, basically, I don't know how to board the problem to make a correct solution… I only achieved to show a static sine wave, so I thought you, guys, could show me the path to walk.

Thanks in advance.

[wwtom]

Hey,
I think your static sine programm looks like

Code: Select all

for(int i = 0; i < 84; i++){
      gb.display.drawPixel(i, (sin(2 * Pi / 360 * i * 5) * 22 + 22));
    }

(Maybe a bit less complicated, but that was just what I did in a few Minutes to help you)
I hope you now what I did there with those numbers.

To make this wave moving, you just have to add a variable, like "im" (imove).

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for(int i = 0; i < 84; i++){
      gb.display.drawPixel(i, (sin(2 * Pi / 360 * (i + im) * 5) * 22 + 22));
    }

Now you just have to add 1 to "im" each time the whole loop finished and the wave will move

http://gph.is/1PuIsWG

Finished programm:

Code: Select all

#include <SPI.h>
#include <Gamebuino.h>
Gamebuino gb;

int im = 0;
float Pi = 3.1415;
void setup() {
  gb.begin();
  gb.titleScreen(F("SIN WAVING"));

}

void loop() {
  if(gb.update()){
    im ++;
    for(int i = 0; i < 84; i++){
      gb.display.drawPixel(i, (sin(2 * Pi / 360 * (i + im) * 5) * 22 + 22));
    }
  }
}

[kerunaru]

Hey,

Code: Select all

for(int i = 0; i < 84; i++){
      gb.display.drawPixel(i, (sin(2 * Pi / 360 * i * 5) * 22 + 22));
    }

(Maybe a bit less complicated, but that was just what I did in a few Minutes to help you)
I hope you now what I did there with those numbers.

If I understood well you are calculating the y position of the pixel based on the sine of a degree times the current index of the for loop in order to obtain a different position on each iteration; I think the times 5 is used to get a higher frecuency in the wave… The rest is just to acommodate the result line on the screen.

So yes, if I put another variable to add to the current index, the wave is going to move as it will have a different y position in function of the value of the "im" variable which is updated after each screen update.

Am I right?

[wwtom]

I couldnt describe it better!
You're right